The present invention relates to a microplate and, more particularly, to a microplate having an array of wells for receiving samples. The present invention also relates to methods for making the microplate.
Trays or microplates with an array of wells are commonly utilized for sample storage and retrieval or for qualitative and quantitative assays in various research and diagnostic procedures. These trays or microplates are generally formed of solid material with molded wells and generally have differing patterns in the array of wells including 8×12 wells with a spacing of 9 mm between centers, 16×24 wells with a spacing of 4.5 mm between centers, and 32×48 wells with a spacing of 2.25 mm between centers. It is well known that different uses of microplates make different demands on the overall form and structure of the microplate. Specifically, the microplates require a specific combination of physical and material properties including rigidity, strength, and straightness required for robotic manipulation; flatness of well arrays required for accurate and reliable liquid sample handling; physical and dimensional stability and integrity during and following exposure to high temperatures; and thin-walled sample wells required for optimal thermal transfer to samples received in the wells. Conventional microplates suffer from various disadvantages. For example, a new mold is required when the size or the pattern of the wells is changed. Furthermore, conventional microplates can not meet the different demands.
U.S. Pat. No. 6,632,653 to Astle discloses a method for performing a reagent protocol using polymerase chain reaction. U.S. Pat. No. 6,878,345 to Astle discloses a method for performing biological assays. In both Astle patents, a carrier tape is utilized to avoid the problems of freeze-thaw cycle. The carrier tape includes a substrate web formed with a plurality of reagent receiving wells and is indexed by human or machine readable indicia for pattern identification. However, the carrier tape can not be directly handled by the automated equipment set up for solid materials conventional trays or microplates.
Thin-well microplates meeting different demands and methods for making such thin-well microplates have been proposed, and examples of which have been disclosed in U.S. Pat. Nos. 6,340,589 and 6,528,302 to Turner et al. Sample wells are joined with the top surface of a skirt and frame portion and/or the peripheries of the holes in the skirt and frame portion, and the upper ends of the sample wells extend beyond the top surface of the skirt and frame portion. When the thin-wall microplate is subjected to a freeze-thaw cycle or other thermal procedures for heating or cooling the samples in the sample wells during tests, the heat transfer rate is not satisfactory, for the upper ends of the sample wells are blocked by the skirt and frame portion and, thus, are not in direct contact with the heating or cooling media. Furthermore, varying temperature zones exist throughout the sample wells that extend through the holes of the skirt and frame portion such that the thermal mass of the skirt and frame portion has adverse affect on the sample wells during heat transfer, for there will be a varying temperature gradient moving down the well due to the thermal mass of the skirt and frame portion.
Thus, a need exists for a microplate that overcomes the deficiencies and problems experienced by prior microplates, that provides satisfactory heat transfer effect for the samples received in the wells and that can be manufactured easily.